Hi and welcome!
If I recall corretly walnut is somewhat balanced and best of both worlds kinda thing. One I really one have a guitar made out of one day for sure. That will probably leave the field wide open.
If you say you play stoner/doom/90s hybrid my first impule is Nailbomb bridge. That one is always described to have 90s agression, a lot of versatility and should be one of the first one to come to mind when talking stoner, while handeling doom nicely too.
Dunno if I could recommend the NB neck though as it is often cited as being the only BKP that really feels scooped.
There are many options to go along with the NB bridge, like for example the Cold Sweat neck, but you would have to give us a bit more info on the tone you want from the neck.
With the WP you always gotta beware of too much bottom end. If that is not a big danger for you (amps and cabs play a big role here) that might work brilliantly too, but you gotta be a bit more carefull with that one.
As for the BD, it should have the sound profile you want but might be too vintage I recon. Again, amp and cab play a big role.